The present invention is directed to a short-action firearm having a unique chamber and bolt assembly for firing a high-powered firearm cartridge. More particularly, the firearm chamber has pressure, length and diametric relationships, cooperative with those of a unique cartridge, enabling propellants to be burned more quickly and completely, thereby producing more energy and muzzle velocity for any given propellant capacity than is possible with most previous designs having the same propellant capacity.
In an article which I published in the January 1996 issue of Shooting Times magazine, I discussed the advantages of certain cartridges previously developed by Ackley, Mashburn, Palmisano and Pindell for improved velocity and accuracy. I also mentioned in the article that I had developed a high-power cartridge by modifying a 1908 Westley-Richards cartridge so as to have a unique, short, fat profile which could, for the first time, compatibly combine high velocity, accuracy and power with the compact, well-balanced and lightweight characteristics of a short-action firearm.
However, I had not at that time recognized the problem of permanent lengthwise cartridge case deformation caused by the severely-rebated, small-diameter rim and resultant large unsupported area of the rear wall of the much larger-diameter Westley-Richards cartridge case. Such cartridge case, when modified as described above to produce the propellant-burning characteristics and internal gas pressure curve profile discussed hereafter, proved incapable of withstanding internal gas pressures of at least about 50,000 psi without permanent rearward deformation of the unsupported area of the rear wall of the case, causing the bolt to bind within the extractor groove.
Also, at that time I had not recognized the importance of any specific maximum limit on the length-to-diameter ratio of a cartridge case necessary to produce the desired propellant-burning characteristics and internal gas pressure curve profile discussed hereafter.
A short-action firearm has a chamber and bolt assembly with unique pressure, length and diametric relationships. The overall length of the chamber has a ratio to a diameter thereof, at a predetermined location on a wide portion of the chamber, of no more than about 4.2. Such diameter is at least about 0.53 inch, and the length of the wide portion of the chamber has a ratio to such diameter of no more than about 3.33.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.